1. Field of the Invention
This invention relates to a cooling device, more particularly, to a cooling device in a miniature motor having a forced-cooling fan, wherein a combined fan and gear, with the fan and gear the portions formed integrally together from synthetic resin, for example, is used in order to make the shaft of the miniature motor as short as possible to minimize the vibration of the shaft rotating at high speed and also to simplify the manufacturing processes of a geared motor with a forced-cooling fan thereby to reduce its cost of manufacture.
2. Description of the Prior Art
In a miniature motor driven at a high speed from a battery, it is highly desirable to make the motor shaft as short as possible to prevent the vibration of the shaft.
Recently, there have been developed quickly chargeable nickel-cadmium type cells provided with relief valves for releasing gas when the cells are overcharged, and such cells are often used to drive electric model airplanes. Since the motor for driving such a model airplane is operated with a current of several amperes, it is desirable that the motor be equipped with a fan for forced cooling thereof to prevent the increase in the resistance of the motor windings.
Generally, in providing a geared motor with a forced-cooling fan, it has been customary to form the gear and the fan separately. This results in a long shaft of the motor, causing undesirable vibration of the shaft in case of the motor rotating at a high speed as when driving a model airplane. It also results in the additional manufacturing process of mounting the fan on the motor shaft and, if the centering in said mounting process is not perfect, it will cause more vibration.